Re: stat: added features: `--files0-from=FILE', `--digest-type=WORD' and `--quoting-style=WORD'

[Pádraig Brady]

On 05/22/2014 09:44 AM, Stefan Vargyas wrote:
> 
> Dear maintainers,
> 
> Since coreutils v8.9 I was using a customized 'stat', which has the additional
> features implied by the command line options and by the format sequence shown
> below:

Thanks for the patch.
It's cleanly implemented in a table driven manner.
However there are a few conceptual issues ...

> 
>   $ stat --help
>   Usage: stat [OPTION]... [FILE]...
>      or: stat [OPTION]... --files-from=F
>   Display file or file system status.
>   ...
>         --digest-type=WORD
>                           when computing file content sums use specified
>                           message digest algorithm: md5, sha1, sha224, sha256,
>                           sha384 or sha512;  when the option is not specified
>                           compute sha1 digests

So you provide the above to essentially munge the checksum into the line for 
easy
comparision with diff etc.  While this is a valid and useful technique,
wouldn't it be better to leverage the existing utilities to join the data like:

  join -j2 <(stat -c '%s  %n' /bin/ls /bin/cp | sort) <(sha1sum /bin/cp /bin/ls 
| sort)

Also diff might not be that general in the presence of many different files,
so you might also find this construct useful:

  tr '\n' '\1' |
  sort |
  uniq -u ...

>   ...
>         --files-from=F    display status of files specified by names in file 
> F;
>                             If F is - then read names from standard input

There is no advantage of supporting this option in stat
as that is only useful when a command needs to process all
file names in a _single invocation_, like when sorting or accumulating etc.
For stat one can efficiently:

  find ... -print 0 | xargs -r0 stat ...

or

  find ... -exec stat {} +

Note also that sort has the --zero-terminated option, as do newer versions of 
join and uniq.

>         --quoting-style=WORD
>                           use quoting style WORD for file names:
>                             literal, locale, shell, shell-always, c, escape
>                             c-maybe, clocale;
>                           when no option is given, use literal style

This could be useful, however there is already the %N option for quoted file 
name.

$ stat -c %N /bin/ls
‘/bin/ls’
$ LANG=C src/stat -c %N /bin/ls
'/bin/ls'

Can you detail the exact use case for this.
If we were to apply this bit I guess it would make sense to only
apply the selection to %N ?

thanks!
Pádraig.